A history professor finds that when he schedules an office hour at the 10:30 a.m. time slot, an average of three students arrive. Use the Poisson distribution to find the probability that in a randomly selected office hour in the 10:30 a.m. time slot exactly four students will arrive.
◦ 0.1328
◦ 0.0618
◦ 0.1680
◦ 0.0489